Maine ? As the recession accelerates and people drive less, collections on toll roads are slowing down. At the same time, maintenance and constructions costs are going up.

That means the 75 agencies that operate toll roads and bridges from Maine to California are under pressure to increase tolls.

HNTB, a nationwide engineering and consulting firm, said a number of the 99 toll roads it monitors had already raised rates last year, including New Hampshire’s turnpikes, the Garden State Parkway in New Jersey, the Pennsylvania Turnpike and New York State Thruway.

Others either raising tolls or contemplating increases this year, in addition to the Maine Turnpike, include the New York State Thruway (again), Ohio Turnpike, Massachusetts Turnpike, New Jersey Turnpike, Kansas Turnpike and John F. Kennedy Memorial Highway in Maryland.

Most turnpike authorities are freestanding entities, one expert said. Toll revenue is required for paying off bonds, in addition to financing maintenance and improvements.